One factor which affects the commercial viability of a particular orthodontic appliance is of course the cost of the appliance. The cost of the appliance is influenced by a number of factors, one of which is the manufacturing costs. With regard to metal brackets, a wide variety of these types are manufactured in two-piece form. Specifically, the body of the bracket, which includes the tie wings, is manufactured as one part (e.g., by metal injection molding ("MIM"), while the other part, a tooth contoured bonding base, is manufactured separately (e.g., by photo etching or by stamping). The body and base are then welded or brazed together about the perimeter of the body. Although this manufacturing method produces brackets which perform suitably in many cases, the associated manufacturing costs may have a tendency to be comparatively high depending upon, for instance, the specific manufacturing sequence and the labor involved therewith. Moreover, corrosion can result from non-passive resistance welds and crevice corrosion sometimes occurs at the interface of orthodontic bodies which are welded to bases. Orthodontic bodies and bases which are joined by brazing require relatively expensive precious metal or noble alloys to avoid this type of corrosion problem.
Another method of manufacturing metal brackets is by MIM. That is, the entire bracket may be molded as a single part. U.S. Pat. No. 5,267,854 refers to such a bracket. The manufacturing costs associated with this particular method may be comparatively high due primarily to the cost of the molds. That is, depending of course upon the configuration of the particular bracket, the molds tend to be relatively complex to design and/or manufacture.
Based upon the foregoing, there continues to be a need for further improvements in the manufacture of orthodontic appliances which have commercially acceptable performance characteristics and which are commercially available at a competitive price.